The tendency of demanded power depends on various factors. Therefore, power facilities are designed according to the peak of the demand so that the power facilities may be normally operated even when the power demand reaches the maximum value. With the power facilities, an attempt is made to meet the demand by electric cell power using an electric cell device when the demand is large and store power in the electric cell device when the demand is small with the environmental problem, the cost problem, etc. taken into account, thereby performing a leveling operation and reducing the peak of power demand. If the peak of the demand may be reduced and the fluctuation of the demand may be leveled as described above, then the demand load rate of power generation in an operation mode in which an output fluctuation may be suppressed as much as possible may be raised, thereby realizing carbon dioxide (CO2) emission lowering and cost reduction.
In the leveling control using an electric cell device, an output target value is set, a residue may be charged in the electric cell device when the demanded power of a load is smaller than the output target value, and a deficiency may be discharged from the electric cell device when the demanded power is larger than the output target value. In this case, there is an example in which the load of a power supply is leveled by measuring the electric energy actually used by the load, and changing the plan of the discharged energy of the electric cell device when the measured value is deviated from an allowable limit. There is also an example in which an output of a power supply and the amount of storage of an electric cell device are detected, and an average value of the output in a preset period is corrected by a target value set depending on the amount of storage, thereby setting an output target value. Furthermore, there is also an example in which an average value of the spent power from the start of the demand timing to the current time based on the information about the spent power, the electric cell device is discharged when the average value exceeds a first specified value, and it is charged when the average value is smaller than a second specified value.
[Patent Document 1] Japanese Laid-open Patent Publication No. 11-41831
[Patent Document 2] Japanese Laid-open Patent Publication No. 2002-17044
[Patent Document 3] Japanese Laid-open Patent Publication No. 2003-299247